Automatic radio tuning mechanism



Aug. 2, 1949. s. H. PROFFITT ET AL AUTOMATIC RADIO TUNING MECHANISM 2 Sheets-Sheet 1 Filed Jan. 8, 1948 fi afb e. Fu n mm w C t n t eH A M 5 P ke m m S b I l ll 1949- s. H. PROFFITT ET AL 2,478,011

AUTOMATIC RADIO TUNING MECHANISM Filed Jan. 8, 1948 W 2 Sheets-Sheet 2 Inventor-S1 Stanleg HProFFitt, James A.Choules,

Their- Attorneg.

Aug. 2, 1949 UNITED STATES PATENT OFFICE AUTOMATIC RADIO TUNING MECHANISM Application January 8, 1948, Serial No. 1,124

10 Claims. 1

This invention relates to automatic tuning mechanisms for radio receivers, and more particularly to an automatic tuner of the sequence type in whch a series of predetermined broadcast stations, to which the tuner is adjustably set in advance, are successively and automatically tuned-in by actuation of a single control switch.

It is an object of this invention to provide an improved compact and highly accurate automatic radio tuning mechanism which is relatively simple in construction and which requires low unidirectional operating potential and hence may be conveniently utilized to provide automatic tuning for automobile radio receivers.

A further object of this invention is to provide an automatic tuning mechanism of the turret type, in which the turret remains stationary and a rotatable finger is caused to abut against various adjustable stops carried by the turret, and hence to serve as the position determining mechanism for the radio receiver tuning elements.

Another object of this invention is to provide such a tuning mechanism that may be utilized for selecting a series of predetermined frequency modulation and amplitude modulation broadcasting stations, and in addition to provide manual tuning for both the frequency modulation and amplitude modulation frequency bands.

Still another object of this invention is to provide a single manually-operated device in conjunction with the aforementioned turret which serves as a maunal tuning means for the receiver in both the frequency modulation and the amplitude moduluation bands, and in addition as an adjusting means for pre-selecting the various broadcasting stations to which it is desired that the tuning mechanism automatically be tuned.

The features of this invention which are believed to be new are set forth with particularity in the appended claims. The invention itself, however, together with further objects and advantages thereof may best be understood by reference to the accompanying drawings, wherein: Fig. 1 shows a panel view of a radio receiver utilizing the proposed automatic tuning mechanism. Fig. 2 shows a view of a radio receiver similar to Fig. 1 with the panel removed. Fig. 3 shows a plan view of the radio receiver. Fig. 4 shows a front view of our improved automatic tuning mechanism. Fig. 5 shows a slightly enlarged view of the automatic tuner similar to Fig. 4, with the front bracket removed. Fig. 6 shows a side view of the tuning mechanism. with several of the components removed to simplify the diagram. Fig. 7 shows a bottom view of the tuner. Figs. 8 and 9 show detail views of various components of the tuning mechanism. Figs. 10a and 10b are diagrams useful in the explanation of the operation of certain components of the tuning mechanism.

Referring now to the drawings, Fig. 1 shows a typical radio receiver utilizing the present invention, and wherein sequential tuning of preset stations may be accomplished by remote switching means of well-known type, which may be actuated by the hand or foot of the operator or in any other desired manner. The radio control panel, as may be seen, is extremely simple and comprises three controls. A control designated as I has two positions and serves to condition the radio receiver for the reception of either amplitude modulation or frequency modulation stations. A control 2 may serve as the usual volume control, and a control 3 is used to tune the receiver manually through either the frequency modulation or amplitude modulation frequency bands and also to pre-set the mechanism so that the receiver may be tuned automatically to broadcasting stations in either the frequency modulation or amplitude modulation bands by sequence tuning. The usual tuning dial is shown at ti, and provision is made to illuminate either the amplitude modulation broadcast or frequency modulation sections of the dial, dependent upon the particular band to which the receiver is tuned.

Fig. 2 shows a view of the receiver similar to Fig. 1 with the front panel and various associated components removed. In this figure the tuning mechanism is shown generally as 5, various electron discharge devices and other electrical components of the receiver are indicated respectively as 6 and I. The control I is coupled to the tuning mechanism 5 by way of arms 8 and 8' and connecting link 9, the rotation of control I causing the tuning mechanism to tune the receiver for the reception of either amplitude modulation or frequency modulation stations, in a manner to be described.

Fig. 3 shows a plan view of the receiver and in this view it can be seen that the control I transmits motion to arm 8 and hence to arm 8' through the link 9 by means of a shaft l0 carried by bearings ll. Tuning in the present example is of the permeable type and a plurality of cores l2 are shifted longitudinally in corresponding tuning coils to tune the receiver. The cores 12 are carried on an arm 13, having fixed thereto a further arm M which carries a pulley l5. The arm l4 and pulley l5 moves back and forth in response to the various tuning positions of the cores [2. One end of a cord I5 is attached to the chassis of the receiver at H, and wound about pulley l5 and about further fixed pulleys I8 and [9. The other end of cord i6 is attached to the free end of a spring '29 which has its other end afiixed to the receiver chassis at 2i. Th cord It carries a pointer 22, and it can be seen that this pointer is moved across the dial l of Fig. 1 and may be so adjusted that for every position of the cores l2, the pointer 22 indicates the corresponding frequency in the frequency modu'a'tion or amplitude modulation band.

A front view of a tuning mechanism "is shown in Fig. 4. The cores [2 of Fig. 3 are shown as being six in number and are causedto move longitudinally in the receiver tuning coils which are mounted on coil forms 22'. The coil forms are carried by a panel :23 which may be or fibrous material, and connection may be made to the coils by way of terminals 24 and 25 through this panel. The panel 23 is fixed'to the tuning mechanism by means of brackets 26, and is mounted thereon by screws '21. The front bracket 28 of the tuning mechanism is mounted to the receiver chassis by any suitable bra'cket -means,'not shown. The bracket 28 carries twelve guide rods 29 which brace together this bracket with a rear bracket in a manner to be described hereinafter. Shaft 3'9 is carried in the bracket 2'8 and this shaft is actuated by control 3 of "Fig. 1. When rotated, the shaft 39 may be made to tune either the frequency modulation or amplitude modulation bands and when pulled out a short distance and rotated this shaft serves to setup the pre-selected station mechanism in the automatic tuner. An interlocking switch 31 is controlled by the shaft 30 and so arranged that when this shaft is in its forward or extended position, theswitch is opened and hence prevents energization of the tuner during the pro-selection set-up .procedure. The bracket 28 also carries twelve-abutment adjusting screws mounted rotatably on fixed bearings at 32. Two of the above-mentioned adjusting screws are utilized for manual tuning of the respective amplitude modulation and frequency modulation bands, and these screws are resiliently mounted on bracket 28 in such a manner that when the tuning device is actuated thereto, either the switch '33 or switch 34 is caused to close-illuminating the suitable section of the dial 4 of Fig. 4.

Referring now to 'Fig. 7 which shows 1a bottom view of the tuning mechanism, as previously stated, front bracket 28 is braced to a rear bracket 35 by twelve guide rods 29. Twelve rotatable abutment adjustment screws 36 are carried :by the brackets 23 and 35, each of the screws 36 carrying a driving pinion 39, an adjustable abutment 49, a locking :nut -M, and compressiontorsion spring 4-2. Rotation of pinion 39 causes abutment 49, nut 4| and spring 42 to move along the screws 36 as a unit, since the guide rods 29 prevent rotation of the above-mentioned abutment nut and spring. The mounting of *the above-described adjustment screws is clearly shown in Fig. 6 wherein it can be seen that "the screws 36 are mounted rotatably between brackets 28 and 35 in fixed bearings 32, each of these screws carrying a driving pinion '39, an adjust-- ment abutment 49, backing nu t 41, spring #2 and a further biasing spring "43.

Refer-ring now to Fig. 8 it can be seen that the shaft 39 is rotatably-supported in bracket 28 and can also be moved a limited longitudinal distance therein. The shaft 39 carries a gear 4 1 which is driven thereby, and in addition this shaft is coupled to a splined shaft 45 by a coupling 46. The coupling to is rigidly carried by the splined shaft 45 and the shaft 39 is rotatably held in this coupling by a key 41. A bracket 48 is fixed on coupling 47B, and "this bracket carries an idler gear 49.

The pinion 39 of any of the abutment screws 36 may be turned by moving shaft 35 forward from-the position shown in Fig. 8 to the position shown in Fig. 9, thus carrying gear 44, and idler gear 49 forward and into engagement with one of the pinions 39, the particular abutment screw 39 which is actuated thereby being determined by the angular position of the splined shaft When idler 99 and pinion 39 fall to mesh, spring 56 allows idler 59 to slide on a stud 5i, and rotation of shaft on causes subsequent meshing of the gears 59 and 39 whch in turn shifts the particular abutment 49 along its associated screw 35. Adjustment of the tuning cores is accomplished by resilientlyengaging an arm 52 against the respective abutment 40, the arm 52 being integral with a tubular shaft 53, and the shaft 53 being in turn rotatably carried by a sleeve 54. The sleeve 54 is fixed to a sliding bracket 55 and may be integral therewith. The shaft 53 is adapted to rotate spline shaft 45 and slidably engages this shaft. It can be seen that as bracket 55 is caused to slide back and forth, shaft 53 and hence arm 2 is carried therewith. Pressed on the end of shaft 53 is an indexing cam 56, having six teeth 56' and twelve detent depressions 51, as shown in Fig. 7.

A manual screw 36 is shown in Fig. 8 and as previously stated two such screws are provided, one for tuning the receiver circuits through the amplitude modulation band and the other for the frequency modulation band. A triple thread may be used on the manual screws in order that the entire tuning range of the respective bands may be covered with a relatively few turns of shaft 39. Screw 35' is spring-urged to the right of the drawing by a spring '55, the tension in this spring being such that when arm 52 engages abutment 49 the screws 36 are moved to the left and stud 32 closes the contacts .33 or 34 illuminating a suitable section of the dial 2 of Fig. v1 as previously described. The movement of screw 36' longitudinally to the left of the drawing by the engagement of arm 52 with abutment 43 :brings the pinion 39 into the same plane as the idler 49, consequentlylin this positionthexid-ler 49 meshes directly with pinion 391, and hence there is no necessity for longitudinal movement of the shaft 39.

Referring now to Fig. 5 which shows an end view similar to Fig. 4 of the tuning mechanism with th bracket 28 removed, this figure shows the pinions 39, abutments 9 and guide rods 29 which are arranged about a circle, concentric .to shaft :39. The shaft 39 drives gear as which in turn drives respective pinions '39 as selected by the idler gear '49, as previously described.

Reference is now made 'to Fig. '6 which shows the tuning mechanism in the manual tuning position. The arm '52 coacts with abutment All causing screw 3% to move to theileft of the drawing-against spring 55', and stud '32 closes switch 33 illuminating the dial 4 of Fig. 1. .As the-screw 36 is moved to the leftofthe drawing, the pinion 39' is brought into the plane-of the idler gear 49 and meshes therewith. The rotation of shaft 3'9 causes screw 26' to rotate and abutment 40' to move longitudinally along this screw. I he longitudinal movement of abutment 40' causes the shaft 52 to slide along the splined shaft 45, hence moving the bracket 55 which in turn changes the position of the cores 12 in the tuning coils 58, and hence adjusting the tuning of the receiver.

The sliding bracket 55? is moved back and forth for automatic tuning by means of a solenoid 59, the solenoid 59 being mounted on a bracket 50 by means of screws ti and the bracket 60 being in turn mounted on the chassis of the receiver. When the coil of solenoid 59 is energized core 62 is drawn into the coil against the tension of sprin 63. Movement of core 52 causes the arm 64 which is pivoted to 35 to be driven thereby, by Way of link 30. The opposite extremity of arm 64 is coupled to the sliding bracket 55 through a link 6?. When the solenoid 59 is energized the sliding bracket is drawn to the right of the drawing, the cores l2 are fully extended and the arm 52 is moved out of engagement with all abutments 00.

Although a solenoid has been shown as the actuated means of the mechanism the invention is not limited thereto, as any driving mechanism such as a motor and cam arrangement may similarly be utilized.

It is contemplated in the present invention to use six adjustin screws 35 for amplitude modulation and six for frequency modulation although the invention is not limited thereto, and it is further contemplated to arrange the amplitude modulation screws alternately with the frequency modulation screws. Therefore, the amplitude modulation abutments are spaced 60 apart. This includes in each instance five preset positions and one manual tuning position.

Amplitude modulation station selection is accomplished by rotating the shaft 53 in steps of 60 thus swinging arm 52 and turning the idler gear as about gear M, this later motion being transmitted by Way of spline'd shaft 45. The above action is accomplished by means of the solenoid ss acting through arm 60 and link 61 on sliding bracket 55. As shown in Fig. 'l bracket 55 is carried slidably on a guide rod 68 by means of a bracket 59, and on a guide angle 10 by means of roller i and further roller placed directly beneath this roller and engaging the opposite side of the guide angle 10. The indexin cam 55 is pressed on the end of shaft 53, which in turn is carried in a sleeve 5 t mounted on the bracket 55. As previously described, the indexing cam 50 has six teeth 55 and twelve detent depressions 5?. As the cam 55 is carried to the right of the drawing under the influence of solenoid 59, roller moves up an incline on the guide angle l0 and the roller 'ii is partially moved out of a detent 5i by arm 12 moving against the tension of spring I3. This occurs as the arm 52 passes beyond the extreme position of any abutment 05?. Soon thereafter teeth 55' engage with a bar it (Figs. 6 and '7), rotating shaft 53 substantially 50. When the solenoid is reieased, bracket 55 moves to the left of the drawing under the influence of spring 63 and as the roller it rolls down the incline 15 the roller it rotates shaft 53 the remaining 10 as it positively engages a detent 51. The arm 52 now engages a different abutment 40 and a different broadcasting station is thereby tuned in by the mechanism.

The above-described action of the various rollers is clearly shown in Figs. 10a and 10b wherein the bracket 55 engages the guide angle 10 by way of rollers 14 and 19. Fig. 10a shows the roller M at the bottom of the incline l5 and rollers ll engaging a detent 57. Fig. 101) shows the roller 74 at the top of the incline 15 thus moving arm 12 against the spring is and releasing the detents from the arresting action of rollers H.

As shown in Fig. '7, the bar 16 is formed integral with a shaft Tl, shaft 17 being rotatably supported by a bracket 18 which in turn is fixed to the supporting bracket of the tuning mechanism. As previously described in connection with Fig. 3, the angular position of shaft 11 is controlled by the arm 8 which is coupled to the control i of Fig. 1.

To traverse the 30 between amplitude modulation and frequency modulation settings, bar 75 is rotated 30 by the aforementioned control i of Fig. 1. On subsequent energization of the solenoid 59, bar it strikes the indexing cam 55 half way down the face of one of the teeth 56' which results in a total rotation, including the action of the detents of 30 in shaft 53, arm 52 idler 49.

This invention therefore provides a relatively simple, compact tuning arrangement which may be utilized to tune a receiver in the amplitude modulation and frequency modulation bands, and in which this tuning may be accomplished either automatically or manually.

This invention further provides a tuning mechanism' in which the settings for predetermined station selection may be changed and adjusted at will, with a minimum of eifort.

The present invention further provides an automatic tuning mechanism in which the turret, comprising the various abutments and adjusting screws concentrically arranged about the rotating arm, is stationary and the only moving parts are the shaft carrying the above-mentioned arm and the associated bracket and linkage arrangement. It is obvious that with such an arrangement, the rotating arm may be accurately mounted and an extremely precise mechanism is obtained for positively tuning a receiver to a pre-set station. In addition the complete action of the mechanism is actuated by a single solenoid, motor or other means and a minimum of power is required due to the abovementioned minimum of moving parts.

While certain specific embodiments have been shown and described it will of course be understood that various modifications m'ay be made without departing from the invention. The appended claims are therefore intended to cover any such modifications as come within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Automatic tuning mechanism comprising a movable controlling member, means for imparting reciprocating rotation to said controlling member, an abutment assembly including a plurality of abutments, an arm carried by said controlling member, means for causing said arm to cooperate with said abutments in a predetermined sequence, said last-mentioned means comprising a cam member carried by said controlling member, and a further member, means for causing said cam member to coast with said further member to rotate said controlling member through a predetermined angle when said controlling member is substantially at the extremity of 9 energization of said electric means when said further shaft member is conditioned to adjust said respective abutments.

10. Automatic tuning mechanism comprising a movable controlling member, said controlling member including a rotatable shaft member having an arm mounted thereon, means for imparting reciprocating motion to said controlling memher, an abutment assembly including a plurality of abutments, said abutment assembly also including manual tuning means, means for causing said arm to cooperate with said abutments in a predetermined sequence, visual indicating means, and switching means associated with said REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,310,720 Wandrey Feb. 9, 19 3 

